Group III-nitride vertically aligned nanowires and nanowire-devices on silicon have recently been developed for solid-state lighting. They have shown various advantages over their counterparts, such as GaN on sapphire,1 GaN bulk substrates,2 SiC,3 and GaN-on-silicon substrates.4 High efficiency phosphor-free white nanowire light-emitting diodes (NW-LEDs) on silicon exhibited nearly zero efficiency droop.5 These InGaN/GaN nanowires and white-emitting LEDs showed negligible quantum confined Stark effect (QCSE), which is desirable for improved quantum efficiencies.6 
Despite the high-quality nanowires and superior devices grown on single-crystalline silicon substrates, there are issues that remain to be addressed. One of the issues is related to the formation of an amorphous SiNx layer when the active nitrogen radicals impinge upon the silicon surface,11 which hinders carriers flow and heat dissipation. The small diameter of the nanowires can cause high junction temperature of NW-LEDs and lasers associated with the high injection current density, as compared to that in conventional planar devices.12 Additionally, the electrons and phonons that carry the heat are confined to one-dimensional transport along the nanowire.13,14 The thermal management of nanowire devices thus can be important to avoiding “thermal droop” because of the high heat flux and carrier de-population from the Qdisks, leading to efficiency roll-over.15 The issue is further aggravated by the fact that, in practical solid-state lighting applications, the operating temperature can be as high as 120° C.,16 Furthermore, significant visible light absorption reduces quantum efficiencies in LEDs on silicon.
Although GaN nano and microstructures have been demonstrated on diamond and amorphous glass,17,18 which address the thermal conductivity and/or absorption issues, respectively. This technique does not simultaneously resolve the absorption, thermal- and electrical-conductivity issues for high-power device operation at elevated temperatures.
Accordingly, there is a need to address the aforementioned issues.